In many motor vehicles, an interlock system is provided to restrict access to certain electrical features. Many vehicles, for example, have high voltage electrical system to power electric motors or other systems.
Interlock systems generally prevent access to high voltage or other systems by shutting down the systems when potentially unsafe conditions are detected. A conventional interlock system generally detects a potentially unsafe condition with a switch connected to an access cover or panel at an access point. The access cover prevents access to a high voltage or the like. When the cover is open, the switch opens to disable the high voltage or other electrical condition. When the access cover is in place, the switch remains closed.
Many conventional interlock systems have more than one access point with more than one interlock. The switches in each of the interlocks are typically connected in series in an interlock loop that is connected to a controller. When all of the interlocks are closed, current can flow through the series interlock loop. With all of the interlocks closed, the controller detects a safe condition and enables the system. If any one or more of the interlocks are open, then current generally cannot flow through the series interlock loop. With an open condition in the interlock loop, the controller disables or otherwise changes the state of the system to prevent access to high voltage or other conditions.
In conducting a repair or analysis of a conventional system that has multiple access points with multiple interlocks, the controller typically only indicates that there is a breach in the series interlock loop, without indicating the location of the breach. That is, the controller in a conventional series interlock system only detects one state corresponding to all interlocks being closed. Service personnel often spend considerable time and effort to analyze and then correct the breach in the interlock system because they can only guess which of the interlocks are breached, and how many interlocks are breached. With four interlocks, for example, in a conventional series interlock loop there are 24 possibilities or 16 possible states of the conventional series interlock loop leading to a number of possible conditions to be manually diagnosed by the technician. Further, in conventional series interlock systems, other conditions such as an open connector or a broken wire in the series interlock loop may also appear as a breached interlock location, thereby further complicating diagnosis of an “open” interlock system.
One conventional solution to the challenge of diagnosing interlock breach problems is to run a separate interlock loop to each interlock, thereby placing the interlocks in parallel rather than in series. This solution has drawbacks in added costs, space, weight, and time for installation, as many additional wires are generally needed to operate the interlocks.
Accordingly, it is desirable to provide a series interlock system with the ability to identify individual breached locations. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.